Incandescent lamps having preformed filament units

ABSTRACT

Axial-geometry incandescent lamps with accurately aligned, selfcentering helical filaments are disclosed, the filaments having heavy end sections which are mechanically deformed to grip a helical center section. Tubular lamp envelopes have a glass center section and metal end sections heat-sealed thereto. Envelopes are produced in quantity by a machine having magazines loaded with envelope components, the components being automatically assembled and united by heat sealing. Envelopes of larger size may employ glass-beaded metal end sections formed before the end sections are assembled with the center section. Rotation of the envelope components during heat sealing ensures seal uniformity and concentricity.

[ 1 Oct. 21, 1975 INCANDESCENT LAMPS HAVING PREFORMED FILAMENT UNITS [76] Inventor: Donald J. Belknap, PO. Box 325,

Mountain Home, N.C. 28758 [22] Filed: June 22, 1973 [21] Appl. No.: 372,535

Related US. Application Data [62] Division of Ser. No. 147,747, May 28, 1971, Pat. No.

[52] US. Cl. 313/315; 313/271; 313/222 [51] Int. Cl. H01K 1/02 [58] Field of Search 313/315, 271, 222

[56] References Cited UNITED STATES PATENTS 2,191,346 2/1940 Greiner 313/315 X 2,222,093 11/1940 Swanson 313/271 X 3,505,556 4/1970 Belknap 313/315 X Primary Examiner--Saxfield Chatmon, Jr. Attorney, Agent, or Firm-Shapiro and Shapiro [57] ABSTRACT Axial-geometry incandescent lamps with accurately aligned, self-centering helical filaments are disclosed, the filaments having heavy end sections which are mechanically deformed to grip a helical center section. Tubular lamp envelopes have a glass center section and metal end sections heat-sealed thereto. Envelopes are produced in quantity by a machine having magazines loaded with envelope components, the components being automatically assembled and united by heat sealing. Envelopes of larger size may employ glass-beaded metal end sections formed before the end sections are assembled with the center section. Rotation of the envelope components during heat sealing ensures seal uniformity and concentricity.

9 Claims, 38 Drawing Figures I........ I I.

US. Patent 00. 21, 1975 Sheet 1 of 8 3,914,640

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FIG 6 US. Patent Oct. 21, 1975 Sheet 2 of8 3,914,640

32 40 FIG 1 34 38 56 I) 36 "II/"m K FIG 12 36A I 40 32 48 FIG 14 US, Patent Oct. 21, 1975 Sheet 3 of8 3,914,640

US. Patent Oct. 21, 1975 Sheet 4 of8 3,914,640

Patent Oct. 21, 1975 Sheet 5 of8 3,914,640

w m F US Patent Oct. 21, 1975 Sheet 7 of8 3,914,640

FIG. 24

28 22 mW 28A 36 lOA 7 VIII!!! IA mm 56 28A will/ m 35 IDA m 10. 36 FIG. 37

US. Patent Oct. 21, 1975 Sheet 8 of8 3,914,640

POSITIGN 3 GLASS TUBING POSITION 2 LOADED POSITION 4 GLASS BEADS GLASS TUBING SEALED SEALED POSITION I POSITION 5 METAL TUBING and GLASS BEADS LOADED 7 5m FIG? 27 Ha. 282/ 40 38 48 5a. 29

T WII In.

48 7 36A mum 31 i 40 38 40 348/ FIG. 32

FIG. &3

INCANDESCENT LAMPS HAVING PREFORMED FILAMENT UNITS This is a divisional application of Ser. No. 147,747, filed May 28, 1971, now US. Pat. No. 3,762,900, granted Oct. 2, 1973.

BACKGROUND OF THE INVENTION This invention relates to incandescent lamps and to methods and apparatus for manufacturing the same. The invention is more particularly concerned with lamps of axial geometry, with the manufacture of filament units and lamp envelopes, and with the precise alignment of the filaments in the envelopes.

Lamps of microminiature size now being manufactured have an envelope comprising two pieces of metal tubing sealed into the ends of a central glass sleeve. The filament consists of a tungsten helix dragged into the envelope through the end pieces and positioned so as to be approximately centered with respect to the central glass sleeve and to have an end extending into each piece of metal tubing. The lamp is sealed by cold-weld pinch-offs through the pieces of metal tubing and the ends of the filament helix extending therein. Such lamps are disclosed in the applicantss prior application Ser. No. 846,466, filed July 31, 1969, now US. Pat. No. 3,736,630, granted June 5, 1973. Such lamp construction and method of filament insertion have made possible the economical production of micronminiature size lamps by eliminating costly hand labor eliminating each lamp. However, because of variations in the very small end openings of the pieces of metal tubing after cutting and processing, neither the points where the ends of the helix contact the metal tubing nor the number of helix turns between the two pieces of tubing can be controlled precisely. This makes it necessary to select and group the lamps from even the same production run according to light output and electrical characteristics.

The applicant has previously disclosed apparatus and methods for making microminiature lamp envelopes of axial geometry in which the metal end pieces are inserted axially into the central glass sleeve from opposite ends and are then heat-sealed to the glass section. Such apparatus and methods are disclosed in the applicants prior application. Ser. No. 760,852, filed Sept. 19, 1968, now US. Pat. No. 3,578,429 granted May 11, 1971. While these apparatus and methods perform admirably in the production of micro-miniature envelopes, it is difficult to obtain even heating of the joints for larger size envelopes and to maintain concentricity.

BRIEF DESCRIPTION OF THE PRESENT INVENTION ment units'which are self-centering in the lamp envelopes and which may be a mass produced with different ratins for insertion in a common size envelope;

Another object of the invention is to provide filament structures employing continuously wound filament wire without straight wire sections, change in helix pitch, or special adaptations.

Still another object of the invention is to provide improved filaments manufactured and fixed within a lamp envelope by means of cold-weld pinch-offs alone, and without affecting the vacuum tightness of envelopes.

Another object of the invention is to provide improved apparatus and methods for manufacturing axial-geometry lamp envelopes, with improved glass tometal and glass-to-glass sealing and improved axial symmetry of the central glass section.

Another object of the invention is to provide improved apparatus and methods for manufacturing envelopes with glass-beaded metal end sections.

Still another object of the invention is to provide improved automatic operation in an envelope-making machine.

Briefly stated, axial-geometry incandescent lamps in accordance with the invention have a tubular envelope with a glass central section and metal end sections. The filament units comprise a length of helical wire joined at its ends to relatively massive terminal members which are mechanically deformed to grip the helical wire. The terminal members serve to align the filament with the axis of the envelope and are fixed to the tubular end pieces of the envelope by cold-weld pinch-offs through the end pieces. The envelopes are assembled seriatim from components dispensed from magazines. In one embodiment lengths of metal tubing which will constitute the end pieces are inserted through corresponding glass beads, which are then heat-sealed to the tubing. These assemblies are then inserted into opposite ends of a length of glass tubing, and the glass beads are heat-sealed to the glass tubing. During the heat sealing operations the components are rotated about their axis to ensure concentricity and uniform sealing.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described in conjunction with the accompanying drawings, which illustrate preferred and exemplary embodiments, and wherein:

FIGS. 1 7 are fragmentary vertical sectional views illustrating the manufacture of filament units;

FIGS. 8 12 are vertical sectional views illustrating the insertion of the filament unit within an envelope and the completion of a lamp; 1

FIGS. 13 15 are vertical sectional views of modified forms of lamps;

FIG. 16 is a persepctive view of a machine for manufacturing lamp envelopes;

FIG. 17 is a side elevation view illustrating the manner in which finished envelopes are discharged from the transport of the machine of FIG. 16:

FIG. 18 is a fragmentary end elevation view of the lower portion of the transport illustrating the drive pulleys;

FIG. 19 is a fragmentary perspective view illustrating an envelope-supporting portion of the transport;

FIG. 20 is an fragmentary end elevation view of the apparatus of FIG. 19;

FIG. 21 is a side elevation view illustrating a portion of the apparatus of FIG. 19 in greater detail;

FIG. 22 is a fragmentary end elevation view illustrating the manner in which lengths of tubing are inserted into glass beads and placed upon the transport;

FIG. 23 is a vertical sectional view illustrating a portion of the apparatus of FIG. 22 in greater detail;

FIG. 24 is a vertical sectional view illustrating the apparatus for inserting beaded metal tubing into a glass sleeve;

FIGS. 25 and 26 are fragmentary perspective views illustrating the lower portions of the bead magazine and the glass tubing magazine, respectively;

FIG. 27 is a diagrammatic view illustrating the positions of the transport during the manufacture of a lamp envelope;

FIGS. 18-32 are diagrammatic views illustrating the steps in the manufacture of an envelope;

FIG. 33 is a fragmentary end elevation view illustrating the manner in which glass beads are guided at the bottom of the bead magazine;

FIG. 34 is a fragmentary side elevation view illustrating the guiding of a glass bead at the bottom of the bead magazine;

FIG. 35 is a fragmentary side elevation view illustrating one form of junction between a filament coil and an end terminal; 7

FIG. 36 is a sectional view taken along line 3636 in FIG. 35;

FIG. 37 is a fragmentary vertical sectional view illustrating another form of filament coil and end terminal junction; and

FIG. 38 is a longitudinal sectional view of a lamp having a filament unit of the type shown in FIG. 35.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, and initially to FIGS. 1-6, filament units of the invention may be manufactured frrom helically coiled filament. wire 10, such as tungsten wire of 0.00025 inch diameter wound upon a mandrel of 0.002 inch diameter. The helically coiled filament wire may be stored upon a spool 12 and drawn off as needed or it may be stored in individual lengths of helically coiled wire. In the form shown in-FIG. 1 filament wire from the spool 12 is passed through an opening in a guide 14 toward the end of a length of metal tubing 16 supported upon a table 18. The tubing may be nickel metal tubing, 0.400 inch in length. 0.015 inch in O. D., and 0.005 inch in I. D. As shown in FIG. 2 the filament wire is inserted a short distance into the end of the metal tubing, and then the smoothly rounded end of an indenting tool -20 is brought downwardly into engagement with the tubing. The tool 20 deforms the tubing as shown at 22 in FIG. 3, several turns being compressed and gripped. The number of turns within the tubing is determined by the insertion. Next the tubing is moved to the right as shown inFIG. 4 to draw a length of filament wire from the spool, and then the wire is cut or burnedas indicated by the cutting tool 24 in order to sever alength of wire A fromthe spool supply.

The unit comprising the length of wire 10A and the metal tubing 16 is then placed in the position shown in FIG. 5, with the filament wire protruding through an opening in a guide 26. A further length of metal tubing 28 supported upon a table 30 is moved to the right so as to insert the free end of the coiled wire 10A into the tubing 28. Next the rounded nose of the tool is brought downwardly upon tubing 28 as shown in FIG.

6 to deform the tubing and cause it to grip the corresponding end of the wire 10A. The finished filament unit 32 is shown in FIG. 7.

FIG. 8 illustrates the filament unit being inserted into an envelope 34 in accordance with the invention. The envelope comprises a central section 36, which may be a glass sleeve of uniform wall thickness, for example, and a pair of tubular end pieces 38 and 40 which are heat-sealed to the ends of the glass section 36. The wall thickness of the glass section is quite small compared to the inner diameter of the glass section, and the length of the glass section is substantially greater than its other diameter. The filament unit 32 can be inserted into the envelope 34 horizontally or dropped in vertically. The filament unit may be slightly longer than the envelope to facilitate insertion, and a wire may be pinched into one end terminal to permit the filament unit to be pulled into the envelope. For vertical insertion the wire may be bent over like a hook to support the filament unit within the envelope temporarily, or one of the tubular terminals of the filament unit may be bent in this manner.

As shown in FIG. 9 the relatively massive end terminals of the filament unit serve to align the filament coil with the axis of the envelope when the filament coil is positioned symmetrically within the glass section. Indenting tools of the type described above then deform the end tubes of the envelope as shown at 42 in FIG. 10 to hold the filament unit in position within the envelope during the completion of the lamp. The lamp unit of FIG. 10 is baked in a vacuum, and then a cold-weld pinch-off tool pinches off one of the end tubes of the envelope as shown in FIG. 11 at 44, severing the end tube and forming a vacuum-tight seal mechanically as described in greater detail in applicants prior US. Pat. No. 3,505,556. The envelope may then be evacuated through the other end tube, and finally that end tube is pinched off in the same manner as shown at 46 in FIG. 12, thereby completing the lamp. FIGS. 13- 15 illustrate three types of envelopes 34A, 34B, and 34C. In FIG. 13 the outer diameter of the metal end pieces is close to the inner diameter of the glass sleeve 36 In FIG. 14 the outer diameter of the metal endpieces 38 and 40 is considerably smaller than the inner diameter of the glass sleeve 36A, and glass beads 48 are sealed between the end pieces 38 and 40 and the glass sleeve 36A. In FIG. 15 there is a still greater disparity between the maximum diameter of the glass section and the metal end pieces, the glass section having ends of reduced diameter to engage the beaded metal tubing.

FIG. 37 illustrates the greater detail the manner in which a metal terminal sleeve 28 may be deformed to grip the end of the helical filament wire 10A and provide excellent mechanical and electrical contact. In this instance opposite sides of the metal tubing are shown deformed symmetrically. FIGS. 35 and 36 illustrate cylindrical solid end terminals which are inserted into the ends of the helical coil and then flattened locally at 50 to embed the filament wire into the end terminal, the filament coil becoming flattened also at the end so as to protrude laterally from the end terminal as shown in FIG. 36. A finished lamp 34D employing a filament unit 32A with solid leads 28A and 16A is shown in FIG. 38.

FIG. 16 illustrates a machine 52 for manufacturing envelopes in accordance with the invention. The components of the envelopes are stacked in magazines. In

aforesaid application Ser. No. 846,466.

the form shown magazines 54 and 56 contain stacked metal tubing for the end sections of the envelopes; magazine 58 contains two stacks of glass beads; and magazine 60 contains a stack of glass sleeves for the central section of the envelope. The transport which carries the components of the envelopes through the successive manufacturing steps is shown at 62. It comprises an arm bifurcated at the top and bottom and pivotally supported at the bottom for movement in a vertical plane about a horizontal axis. The pivot pin is shown at 64 in FIG. 18 supported by a U-shaped bracket 66 upon the frame 68 of the machine. The lower bifurcations 70 and 72 of the transport arm are themselves bifurcated to embrace pulleys 74 and 76 fixed to the pin 64. A central pulley 78 is also fixed to the pivot pin and is driven by a belt 80 from an electric motor (not shown) as indicated in FIG. 17, thereby to drive both of pulleys 74 and 76. The pivot pin 64 is free to turn within journals upon the lower bifurcations 70 and 72, so that the rotation of the pivot pin does not affeet the motion of the transport arm.

The transport arm is moved forwardly by a rod 82 and rearwardly by a spring 84 as indicated in FIG. 17. One end of the spring is attached to a tang 86 fixed to the rear surface of the transport, and the other end is fixed to the frame. The rear end of rod 82 is driven by a cam of a conventional cam drive 87 indicated in FIG. 16, dash line 88 designating the connection from the cam drive to rod 82, which is supported on the frame for forward and backward reciprocating movement. Such cam drives are conventional in the machinery arts, a typical drive being illustrated in the applicants As shown therein, the cam drive may comprise a horizontal shaft extending laterally at the rear of the machine and having a series of parallel cams fixed thereto, the shaft being driven by an electric motor (separate from the motor which drives the belt 80 of FIG. 17), and the cams being shaped and phased to move cam follower shafts at the proper times in accordance with predetermined patterns. As will be seen hereinafter, rod 82 and the associated cam causes the transport 62 to move incrementally from a rearward position to a forward position, the movement being interrupted at different stations for the purpose of operations to be described. Thereafter, the transport is retracted to the rearward position by the spring 84.

Pulleys 74 and 76 drive belts 90 and 92, which pass over and turn corresponding pulleys 94 and 96 at the top of the transport. (See FIGS. 16 and 17.) The upper bifurcations 98 and 100 (see FIG. 22) are, like the lower bifurcations, again bifurcated to embrace the pulleys 94 and 96, which are fixed to hubs 102 and 104 joumaled in the upper bifurcations. See FIGS. 19, 20 and 23. The hubs are provided with central bores 106 and 108 (for a purpose to be described) and carry eccentric platforms 110 and 112 at their inner ends.

The cross-section of each platform is semicircular (see FIG. 21) and each platform has a longitudinal groove, such as the groove 114 shown in FIGS. 19-21, the groove constituting an extension of the corresponding hub bore. Set into the hub below the groove is a magnet 116, the groove being defined between a pair of plates 117 screwed to the surface of the platform.

As shown in FIGS. 19-21, the inner side of each platform is provided with a vertical plate 118 supported for pivotal movement by a pin 120. This movement is limited by a slot 122 in the plate through which a stud 124 extends from the platform. A spring 126 normally urges the plate 118 to the position illustrated in FIG. 21, one end of the spring being attached to a screw 128 fixed to the platform, and the other end of the spring being fixed to a horizontal tang 130 struck from the plate 118 as shown in FIG. 20. The spring 126 passes about the cylindrical surface of the platform. By this arrangement the plate is capable of being turned about the pivot pin 120 until the stud 124 engages the end of the slot 122 opposite to that with which it is shown engaged in FIG. 21, the spring 126 being stressed during this pivotal movement of the plate relative to the platform 110 and retracting the plate to the position shown in FIG. 21 when the plate is released. The plate is bifurcated to provide a slot 132 between a longer arm 134 and a shorter arm 136. The plate 118 normally rotates with the platform 110 until it is held from such movement as will be described later.

FIGS. 27 32 illustrate diagrammatically the operations performed for different positions of the transport 62. Details of the steps performed will be described hereinafter, but it is helpful to understanding of the manufacturing process of the invention to describe the steps broadly at this point. As shown in FIG. 27, at the rearward position of the transport 62, position 1, metal tubing and glass beads are loaded upon the transport. The tubing is shown at 38 and 40 in FIG. 28 and the beads at 48. At position 2 the glass beads are heat sealed to the metal tubing. This is indicated in FIG. 29, heat being supplied by the tiny flames 138. At position 3 glass tubing is loaded upon the transport and the beaded metal tubing is inserted into the ends of the glass tubing as shown in FIG. 30. At position 4 the glass tubing is heat sealed to the beads, as indicated in FIG. 31, heat being supplied by the tiny flames 140. Finally, at position 5 the completed envelope unit (shown in FIG. 32) is unloaded from the transport.

FIGS. 22 and 23 illustrate the operation at position 1. At this position the transport 62 is stationary, with the bores 106 and 108 aligned with push rods 142 and 144. The push rods reciprocate in the corresponding horizontal bores of blocks 146 and 148 supported upon the frame of the machine. The push pins extend from bases 150 and 152 which are moved toward and away from the outer end of the blocks 146 and 148, respectively, by rods 154 and 156. The rods are mounted horizontally on the machine frame for pivotal movement in a horizontal plane. The rods extend rearwardly, where they are pivotally mounted and driven from the cam drive 87 (FIG. 16) as indicated by the dash lines 158 and 160. The base portions 150 and 152 of the push pins are engaged by yokes.162 and 164 freely pivoted upon the corresponding rods for movement about a vertical axis. Thus, limited pivotal movement of the rods 154 and 156 is converted to reciprocative movement of the push pins 142 and 144.

FIG. 23 illustrates the push pins 142 and 144 in their retracted position, that is, with the base portions 150 and 152 remote from the blocks 146 and 148. In this position the push pins are ready to engage lengths of metal tubing loaded in the magazines 54 and 56. At the bottom of each magazine is a table 166 or 168 which supports the lowermost piece of metal tubing in the magazine. At the appropriate time the push pins 142 and 144 move toward each other and engage the lowermost piece of tubing in each of the magazines 54 and 56, pushing the tubing through the bores 106 and 108 of the transport and on to the grooves 1 14 of the transport platforms (see FIGS. 19-21) where they are held by the magnets 116. The width of the grooves 114 is such as to align the tubing precisely with corresponding glass beads at the bottom of the magazine 58.

As shown in FIG. 25, the bottom of the magazine 58 is provided with a cantilevered guide block 170 and a pair of forwardly extending channels 172 and 174. Openings 176 and 178 are provided below the front plate 180 of the magazine to permit glass beads to enter the channels 172 and 174. The metal tubing is inserted into a glass bead at the entrance of the channels as shown in FIG. 33. Then, as the transport 62 moves forwardly from position 1 toward position 2 (FIG. 27), the glass beads are guided by the channels, the metal tubing moving along the curved upper edges 182 and 184 of the guide block 170, the curvature of these edges (see FIG. 34) accommodating the arcuate movement of the transport 62 indicated in FIG. 27. Before the transport can move from position 1 toward position 2, the push pins 142 and 144 must, of course, be withdrawn to the position illustrated in FIG. 23.

As noted previously, at position 2 (FIG. 27) tiny flames 138 are provided for heat sealing the glass beads to the metal tubing. These flames are provided by a burner 186 (FIG. 22) located centrally of the bifurcations 98 and 100 of the transport 62 so that the transport may pass by the burner. A similar burner 188 is shown in greater detail in FIG. 16 and will be referred to hereinafter. Both burners are supported upon the longitudinally extending member 190 and are fed from a longitudinally extending gas pipe 192.

It is desired that the glass beads 48 be uniformly and concentrically sealed to the metal tubing 38 or 40. In order to accomplish this purpose the platforms are rotated during the heat-sealing operations so that the pieces of metal tubing turn about their axes. Such rotation is indicated in FIG. 19. The motor which drives belt 80 (FIG. 17) is started and stopped by a cam of the cam drive to effect rotational movement of the component platforms 110 and 112 at the heat-sealing positions and when the completed envelope units are to be unloaded from the transport.

The operation at position 3 (FIG. 27) is illustrated in FIG. 24. Here push pins 194 and 196 insert the beaded metal tubing into a glass sleeve. In FIG. 24 the beaded metal tubing 38 and 40 is shown supported upon the platforms 110 and 112 and the push pins 194 and 196 are shown retracted. At the appropriate time the push pins move toward each other, engage the ends of the metal tubing, and insert the metal tubing into a glass sleeve at the bottom of the magazine 60. The push pins 194 and 196 reciprocate in horizonatl bores of blocks 198 and 200 (FIG. 16) supported upon the frame with the bores aligned with the bottom of the magazine 60. During insertion of the beaded metal tubing into the glass sleeve, the bores 106 and 108 of the transport are of course aligned with the bores of the blocks 198 and 200. Push pins 194 and 196 project from base portions 202 and 204 supported by members 206 and 208 upon rods 210 and 212 in the manner previously described with respect to the operation at position 1. The rear ends of rods 210 and 212 are fixed to vertical pins 214 (only one of which is shown-in FIG. 16) journaled upon the frame. The lower ends of pins 214 are fixed to cranks 216 driven from the cam drive 87 as indicated by the dash lines 218 and 220.

Y As shown in FIG. 26, the bottome of magazine 60 is provided with a guide block 222 having a central channel 224 for guiding the glass sleeves. Openings 226'and 228 are provided at the bottom of magazine 60 to permit the beaded metal tubing to be inserted into the ends of a glass sleeve at the bottom of the magazine. When the transport moves forwardly, the glass sleeve is guided by channel 224, and the metal tubing passes over the edges 230 and 232 of the guide block, the edges being contoured to accommodate the arcuate movement of the transport 62 between position 3 and position 4 (FIG. 27).

The heat-sealing of the glass tubing to the glass beads (position 4 of FIG. 27) illustrated in FIG. 31 is accomplished by means of the burner 188 (FIG. 16). The tiny flames 140 are located at the apertures 234 and are simply tiny gas flames. As noted above, during this heat-sealing operation the platforms 1 10 and 1 12 of the transport are rotated to ensure uniform and concentric seals. Although the platforms may be rotated continually during the manufacturing steps, it is preferred to interrupt the rotation to prevent the glass beads from walking upon the metal tubing prior to sealing thereto and to prevent similar walking of the glass sleeve prior to sealing to the glass beads.

Unloading the complete envelope unit from the transport is accomplished at position 5 (FIG. 27 As shown in FIGS. 16 and 17, at this position an unloading mechanism 236 is mounted on the frame. The unloading mechanism comprises a plate 238 extending upwardly and rearwardly from the frame and having a tip 240 adapted to engage the tip 242 of the longer arm 134 of each plate 118. The platforms are kept rotating as the transport approaches the unloading mechanism, and when the tips 242 of the plates 118 engage the tip 240 of plate 238, the plates 118 are held against rotation while the platforms continue to rotate. The platforms turn until the studs 124 move to the opposite ends of slots 122, biasing the springs 126 and then the belts 90 and 92 and/or the belt 80 merely slip as the driving motor continues to rotate. The turning of the platforms and 1 12 relative to the plates 118 causes the slots 132 to turn away from parallelism with the platforms and thus to pull the metal tubing of the finished envelope unit away from the holding magnets 116. The envelope unit thus freed from the magnets slides down the inclined slots 132 onto a ramp 244 suspended from plate 238 and drops from this ramp into a receptacle 246. Then the transport 62 is retracted by the spring 84, and wwhen the tips 242 of the plates 1 18 clear the tip 240 of plate 238, springs 126 return plates 118 to their original position (FIG. 21) at which the slots 132 are parallel to the platforms. The transport returns toposition 1 to begin the manufacture of the next envelope.

A typical lamp envelope in accordance with the invention may have a glass central section 7.5 mm long and 5 mm in diameter and 3 mil wall thickness. The metal end sections may have 0.045 inch OD. and 0.028 inch LD. and may project 2.5 mm out from the glass section. The spacing between the inner ends of r sections and corresponding filament lead diameters are as follows:

Filament leads Envelope Ends Solid .002 in. Nickel Wire .015 in. OD. X .005 in 1D. Solid .005 in. Nickel Wire .022 in. OD. X .010 in ID. Tubular .015 OD. X .005 ID. .030 in. OD. X .018 in 1D. Tubular .022 OD. X .010 ID. .045 in. OD. X .028 in 1D. Tubular .030 OD. X .018 ID. .060 in. OD. X .04 in 1D.

It is apparent that the outer diameter of the filament leads is slightly less than the inner diameter of the envelope ends, thus ensuring self-centering when the envelope ends are symmetrically pinched onto the filament leads. The filament units are made without soldering, brazing, welding, skip-forming, or hooking, and without requiring special end terminals.

The envelopes of the invention are complete before insertion of the filament unit, except for the end pitchoffs, and the filament units are complete before insertion in the envelopes, thus facilitating automated manufacturing of the lamps. No brazing, soldering, welding, or heatsealing is required to complete the lamps after the filament units are inserted, and in fact the only heating required utilizes tiny localized flames at one side of the components of the envelope, so that there is no melting and deformation beyond the regions to be sealed.

The invention thus provides incandescent lamps or the like of great precision, economically, and in a wide range of sizes.

While preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that changes can be made in these emconductive tubes, and a coil of filament wire with a plurality of turns at its ends extending into said tubes, respectively, said tubes having indentations formed 'before insertion of said filament unit into said envelope substantially compressing said turns and joining said coil to said tubes mechanically and electrically.

2. A pre-formed filament unit for insertion into a preformed lamp envelope, said filament unit comprising a coil of filament wire, and a pair of longitudinally spaced leads which are relatively massive in comparison to said coil, said coil having a plurality of turns at the ends thereof extending over the adjacent ends of said leads, respectively, said leads and said turns being substantially flattened before insertion into said envelope at regions thereof and thereby joined mechanically and electrically.

3. A filament unit in accordance with claim 2, wherein said turns are embedded in the flattened leads.

4. A filament unit in accordance with claim 2, wherein said leads are flattened at localized regions and are substantially round at opposite sides of said regions.

5. An incandescent lamp or the like comprising a tubular envelope having an insulating central section and a pair of conductive terminal sections extending oppositely from said central section, and a filament unit including a pair of longitudinally spaced conductive tubes and a coil of filament wire with a plurality of turns at the ends thereof extending into said tubes, respectively, said tubes having indentations substantially compressing said turns and joining said coil to said tubes mechanically and electrically, said terminal sections having cold-weld pinched-off ends beyond said central section, said pinched-off ends gripping said tubes and sealing said envelope.

6. An incandes lamp or the like in accordance with claim 5, wherein said central section is a thin wall cylindrical glass tube heat-sealed to said terminal sections.

7. An incandescent lamp or the like comprising a tubular envelope having an insulating central section and a pair of conductive terminal sections extending oppositely from said central section, and a filament unit including a coil of filament wire and a pair of longitudinally spaced leads which are relatively massive in comparison to said coil, said coil having a plurality of turns at the ends thereof extending over the adjacent ends of said leads, respectively, said leads and said turns being substantially flattened at regions thereof and thereby joined mechanically and electrically, said terminal sections having cold-weld pinched-off ends beyond said central section, said pinched-off ends gripping said leads and sealing said envelope.

8. An incandescent lamp or the like in accordance 'with claim 7, wherein said turns are embedded in the flattened leads.

9. An incandescent lamp or the like in accordance with claim 7, wherein said central section is a thin wall cylindrical glass tube heat-sealed to said terminal sections. 

1. A pre-formed filament unit for insertion into a pre-formed lamp envelope of a microminiature lamp, said filament unit comprising a pair of longitudinally spaced conductive tubes, and a coil of filament wire with a plurality of turns at its ends extending into said tubes, respectively, formed before insertion of said filament unit into said envelope said tubes having indentations substantially compressing said turns and joining said coil to said tubes mechanically and electrically.
 2. A pre-formed filament unit for insertion into a pre-formed lamp envelope, said filament unit comprising a coil of filament wire, and a pair of longitudinally spaced leads which are relatively massive in comparison to said coil, said coil having a plurality of turns at the ends thereof extending over the adjacent ends of said leads, respectively, said leads and said turns being substantially flattened before insertion into said envelope at regions thereof and thereby joined mechanically and electrically.
 3. A filament unit in accordance with claim 2, wherein said turns are embedded in the flattened leads.
 4. A filament unit in accordance with claim 2, wherein said leads are flattened at localized regions and are substantially round at opposite sides of said regions.
 5. An incandescent lamp or the like comprising a tubular envelope having an insulating central section and a pair of conductive terminal sections extending oppositely from said central section, and a filament unit including a pair of longitudinally spaced conductive tubes and a coil of filament wire with a plurality of turns at the ends thereof extending into said tubes, respectively, said tubes having indentations substantially compressing said turns and joining said coil to said tubes mechanically and electrically, said terminal sections having cold-weld pinched-off ends beyond said central section, said pinched-off ends gripping said tubes and sealing said envelope.
 6. An incandes lamp or the like in accordance with claim 5, wherein said central section is a thin wall cylindrical glass tube heat-sealed to said terminal sections.
 7. An incandescent lamp or the like comprising a tubular envelope having an insulating central section and a pair of conductive terminal sections extending oppositely from said central section, and a filament unit including a coil of filament wire and a pair of longitudinally spaced leads which are relatively massive in comparison to said coil, said coil having a plurality of turns at the ends thereof extending over the adjacent ends of said leads, respectively, said leads and said turns being substantially flattened at regions thereof and thereby joined mechanically and electrically, said terminal sections having cold-weld pinched-off ends beyond said central section, said pinched-off ends gripping said leads and sealing said envelope.
 8. An incandescent lamp or the like in accordance with claim 7, wherein said turns are embedded in the flattened leads.
 9. An incandescent lamp or the like in accordance with claim 7, wherein said central section is a thin wall cylindrical glass tube heat-sealed to said terminal sections. 